digit reverse

All my greetings to everyone.
With a lot of respect to all members of this forum ,please i'm struggling since already many days to solve this problem.In fact how can we reverse a number (e.g 12345 to 54321)using only looping without array nor pointer or other advanced codes.Also for a number like 1000 it must be 1 inspites of 0001.
thank you for your support Assalam